GROWTH OF A 1ST ORGANIC PHOTOREFRACTIVE CRYSTAL

Photorefractive, doped (greenish) 2-cyclooctylamino-5-nitropyridine (COANP) crystals were obtained from a [TCNQ]22- enriched, supercooled melt. Growth upon fully immersed or pulled, c-oriented seeds produced either triangular plates or nearly an isometrical habitus, respectively. When using cut, polished and etched c-plates, growth of pure or doped COANP was observed only at the pyroelectric (-) end of the c-axis (DELTAT > 0). The photorefractive saturation diffraction efficiencies ranged from 0.1-1%, writing times were in the order of 10 min at 100 MW/cm2.